This invention relates to toe holders for safety ski bindings and in particular to toe holders providing for movement vertically with respect to the surface of a ski, as well as laterally.
For a skier's maximum safety and convenience, it is important that, while skiing, each ski boot is rigidly fixed with respect to the ski. Additionally, to minimize injury to the skier, it is important that the ski boot is disengaged from the ski in the event of imminent fall. To achieve these goals, safety ski bindings have been developed for releasing a ski boot from a ski when applied forces exceed a predetermined value.
Toe holders for safety ski bindings have been designed to achieve release of the toe portion of a ski boot from the ski when predetermined forces in the plane of the ski surface which act to twist the skier's leg are applied. It is useful to have a toe holder which provides for lateral movement with the boot as lateral forces are applied to the boot and, in addition, returns to its skiing position on removal of the applied force. Such a toe holder provides several advantages. When a ski boot is released from the ski, the toe holder will return to a position in which it is ready to again receive the ski boot. This minimizes the need to manually reset the toe holder, a task which is quite awkward and inconvenient in a typical skiing environment. A second advantage of such toe holders is that they may assist in absorbing applied forces which, though insufficient to necessitate release of the ski boot from the ski, may inhibit maximum skiing comfort and safety. This is achieved because the toe holder provides some give to the ski boot, allowing limited lateral movement without releasing the boot, followed by return of the toe holder and the boot to the normal skiing position.
A problem that has been encountered with toe holders as described above is that vertical forces acting on the skier's leg often create frictional forces in the toe holder which inhibit lateral movement of the sole engaging unit and, thus, inhibit appropriate release of the ski boot from the ski. The toe holder often comprises a housing fixed with respect to the ski and having an axle perpendicular to the top surface of the ski. The sole engaging unit of the toe holder is pivotally mounted on the axle, providing for lateral movement of the toe of the ski boot. This accomodates that component of applied force which acts in the plane of the top surface of the ski, however, applied forces acting on the ski do not generally act strictly in the plane of the ski, but also have a vertical component. This vertical component may act on the sole engaging unit in such a manner that frictional forces arise between the pivotally mounted sole engaging unit and fixed parts of the toe holder. These frictional forces inhibit lateral movement of the sole engaging unit, for it is necessary for an applied force to exceed both the frictional force and the predetermined release force before release may be achieved. In this manner, forces dangerous to the skier may be applied without having release of the ski boot from the ski.
Frictional forces also may arise when snow or other foreign matter gets between the bottom of the ski boot and the top surface of the ski. The toe holder is height-adjusted to receive the toe of the ski boot when the sole of the boot is flush against the ski. With foreign matter between the sole and the ski, the toe of the boot will be higher than the toe holder setting. A downward force must then be exerted to urge the toe into the sole engaging unit, causing an upward vertical force to be exerted against the sole engaging unit. Again, this vertical force may cause frictional forces which inhibit lateral movement of the ski boot and its release from the ski. Improper height adjustment of a toe holder may also introduce such frictional forces.
Furthermore, there are instances where purely vertical forces are applied to the toe piece by a skier's boot--such as in the event of a backward fall--when release of the binding is desired. Neither bindings which do not open in response to purely vertical forces, nor complex bindings which do open in such an event, are satisfactory.
Toe holders proposed in the art do not deal satisfactorily with the problem of frictional forces while providing the above discussed beneficial characteristics. German Application DE PS No. 1,578,999 (Wunder) proposes a toe holder having a sole engaging unit that is both axially and pivotally mounted, however, because of its design, the shock sensitivity of that toe holder is unsatisfactory. Additionally, it does not provide for automatic return of the toe holder to the skiing position on release of the ski boot from the ski.
U.S. Pat. No. 3,027,173 (Beyl) proposes toe holders designed to provide for lateral movement of a ski boot toe and for automatic return to the skiing position. However, no provision is made to accommodate the vertical component of applied force, thus such toe holders do not deal with the problem of frictional forces which may inhibit appropriate release of the ski boot. The fact that the toe holder is biased towards its skiing position enhances the danger created by the frictional forces.
U.S. Pat. No. 4,095,821 (Salomon) proposes toe holders designed to accommodate both torsional and vertical forces. However, when set at low release values such toe holders do not fix the toe of the ski boot rigidly to the ski, instead allowing the toe some vertical movement, referred to as "swimming". Additionally, construction of toe holders according to that disclosure is quite expensive.
This invention provides a toe holder having a sole engaging unit which is movable laterally about a pivot axis and also axially along that pivot axis. The axial movement is provided to compensate for vertical forces applied to toe of a ski boot. With a toe holder according to this invention in its skiing position, vertical movement of the ski boot toe is restricted, thus inhibiting the problem of "swimming" of the toe. A toe holder according to the preferred embodiment of this invention is inexpensive to construct and its design provides for a minimum of potential mechanical problems.